---
permalink: "/2011/10/28/CouchDB-And-MongoDB-Performance/"
layout: post
date: 2011-10-28
title: "CouchDB And MongoDB Performance"
tags: [mongodb, performance]
---
<p>I wanted to follow up <a href="https://www.openmymind.net/2011/10/27/A-MongoDB-Guy-Learns-CouchDB/">yesterday's detailed (and objective?) post</a> on CouchDB with some basic benchmarks. I know people hate these types of benchmarks. But I do think it's good to have some very high level idea about these things. Also, both CouchDB and MongoDB have a bulk-api, which is useful for some tasks, but I think most web apps are dealing with fairly small and independent pieces of information. The code is a very poor simulation of the two main queries used in a game engine.</p>

<p>For the record, journaling is enabled in MongoDB <strong>and</strong> I'm doing a full fscync on each insert (the ruby driver doesn't support journal commit yet (which would be faster than a full data file fsync)?! guess what I'm doing next...)</p>

<p>The MongoDB code:</p>
{% highlight ruby %}require 'mongo'
require 'benchmark'

db = Mongo::Connection.new.db("test")

app_ids = Array.new(10){|i| BSON::ObjectId.new}
scores = db.collection("scores")
scores.ensure_index([['appid', Mongo::ASCENDING], ['points', Mongo::DESCENDING]])

Benchmark.bm do |x|
  x.report do
    10000.times do |i|
      if i % 2 == 0
        scores.insert({:appid => app_ids.sample, :points => rand(100000), :dated => Time.now - rand(100000), :user => i.to_s}, {:safe => true, :fsync => true})
      else
        scores.find({:appid => app_ids.sample}).sort([:points, :descending]).limit(20).skip(rand(20)).to_a
      end
    end
  end
end

    user     system      total        real
6.600000   1.040000   7.640000 ( 12.290563){% endhighlight %}


<p>The CouchDB code:</p>
{% highlight ruby %}require 'couchdb'
require 'uuid'
require 'benchmark'

server = CouchDB::Server.new 'localhost', 5984
database = CouchDB::Database.new server, 'test'

database.delete_if_exists!
database.create_if_missing!
app_ids = Array.new(10){|i| UUID.new.generate}

design = CouchDB::Design.new database, 'application'
view = CouchDB::Design::View.new design, 'scores_by_points', 'function(doc) { emit([doc.appid, doc.points], null); }'
design.save

Benchmark.bm do |x|
  x.report do
    10000.times do |i|
      if i % 2 == 0
        doc = CouchDB::Document.new database, :appid => app_ids.sample, :points => rand(100000), :dated => Time.now - rand(100000), :user => i.to_s
        doc.save
      else
        app_id = app_ids.sample
        scores = view.collection(:startkey => [app_id], :endkey => [app_id,{}], :descending => false, :limit => 10, :include_docs => true)
        scores[0] # i believe the data isn't loaded until you actually request the 1st item
      end
    end
  end
end

     user     system      total        real
22.800000   6.040000  28.840000 (177.352028){% endhighlight %}

<p>Again, being a CouchDB nub, I possibly did something very stupid (beyond running and posting yet another stupid benchmark), so I welcome any corrections to the code</p>

<p>Oh, and I know my blog dates are wrong...it's a mistake which has proven a slippery slope</p>
